Television programs, plays, and other audiovisual types of presentations often include both an audio component and a visual component, each of which conveys information to a viewer. Closed captions may be provided for audiovisual programs and presentations in order to allow people with impaired hearing to follow the audio component of the program or presentation. Similarly, an audio description of the presentation may be provided to enable people with impaired vision to follow the visual component of the program or presentation. The provision of such an audio description for television programs is referred to as described television services.
Currently, described television services are not widely available. Several television stations, such as WGBH (Boston, Mass.), provide some described television programs using the second audio program (SAP) of these television programs to transmit the description information.
Described television programs using SAP are currently produced using a process as follows. First, an original tape of the final version of the program, including all dialogue and sound effects, is obtained from a network. If the copy includes a SAP track, for example, a Spanish version of the audio track of the program, this track is lost in the process of providing description information. Second, editors prepare concise, typewritten descriptions of the scenes of the program. Third, one or more professional speakers read the descriptions. Typically, a single speaker reads the descriptions in a soft voice, almost as if he/she was whispering the scene details to the blind viewer. Fourth, the "final" audio track from the original program is re-mastered to be monophonic (SAP can only carry a mono signal) and to include the descriptions as high fidelity monophonic signals. This re-mastering process requires a broadcast quality audio facility. Fifth, the original program is re-mastered to record the SAP track along with the other signals (e.g., the program's video and audio signals) which, according to present television capabilities, may be compressed digital audio stereophonic signals. Finally, the new tape, which is a "generation" down from the original program tape, is returned to the network.
Once the network has received the tape, it may either broadcast the new tape or "slave" the original tape and the new tape together using two tape decks and coordinating the two signals using the standard (SMPTE) time code of the tapes. In the "slave" process, the original tape is used to provide the video and sound (e.g., stereo) of the program, and the new tape is used to provide the SAP track for the program which is inserted into the signal at broadcast time. The slave process has an advantage in that, if the original program has a SAP track (e.g., a Spanish SAP), the original SAP track may be used on some occasions and the description SAP track on other occasions.
There are also audio tape decks that may be slaved to video tape decks to provide the description SAP track for the program. The use of an audio tape player has an advantage in that it eliminates the need to re-master the audio track of the original program as described above.
Thus, since the known method of providing described television services is cumbersome, there is a need for a method of providing described television services by which the descriptions are easily produced and transmitted to viewers.